From: Joel Stanley joel@jms.id.au
[ Upstream commit d46fddd52d11eb6a3a7ed836f9f273e9cf8cd01c ]
SCOM error handling is made complex by trying to pass around two bits of information: the function return code, and a status parameter that represents the CFAM error status register.
The commit f72ddbe1d7b7 ("fsi: scom: Remove retries") removed the "hidden" retries in the SCOM driver, in preference of allowing the calling code (userspace or driver) to decide how to handle a failed SCOM. However it introduced a bug by attempting to be smart about the return codes that were "errors" and which were ok to fall through to the status register parsing.
We get the following errors:
- EINVAL or ENXIO, for indirect scoms where the value is invalid - EINVAL, where the size or address is incorrect - EIO or ETIMEOUT, where FSI write failed (aspeed master) - EAGAIN, where the master detected a crc error (GPIO master only) - EBUSY, where the bus is disabled (GPIO master in external mode)
In all of these cases we should fail the SCOM read/write and return the error.
Thanks to Dan Carpenter for the detailed bug report.
Fixes: f72ddbe1d7b7 ("fsi: scom: Remove retries") Link: https://lists.ozlabs.org/pipermail/linux-fsi/2021-November/000235.html Reported-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Joel Stanley joel@jms.id.au Reviewed-by: Eddie James eajames@linux.ibm.com Link: https://lore.kernel.org/r/20211207033811.518981-2-joel@jms.id.au Signed-off-by: Joel Stanley joel@jms.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/fsi/fsi-scom.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c index da1486bb6a14..3b427f7e9027 100644 --- a/drivers/fsi/fsi-scom.c +++ b/drivers/fsi/fsi-scom.c @@ -289,7 +289,7 @@ static int put_scom(struct scom_device *scom, uint64_t value, int rc;
rc = raw_put_scom(scom, value, addr, &status); - if (rc == -ENODEV) + if (rc) return rc;
rc = handle_fsi2pib_status(scom, status); @@ -308,7 +308,7 @@ static int get_scom(struct scom_device *scom, uint64_t *value, int rc;
rc = raw_get_scom(scom, value, addr, &status); - if (rc == -ENODEV) + if (rc) return rc;
rc = handle_fsi2pib_status(scom, status);